Orientation of particles in elastomer materials



April 4, 1967 ,p c 1 ETAL I 3,312,763

ORIENTATION PARTICLES IN ELASTOMER MATERIALS Filed Nov. 10, 1964 2 Sheets-Sheet 1 INVENTORS Dona \d PeccenH Georqe. De 6vo55 ATTORNEYS April 4, 1967 PECCERlLL ETAL 3,312,753

' ORIENTATION OF PARTICLES IN ELASTOMER MATERIALS Filed Nov. 10, 1964 2 Sheets-Sheet 2 AC. CONTROLLER RC.

D C D.C. .u /20 AAA AA AAA HM ,Nx 1 \A o 120 loo W7, IZZ n2 yvv vvv VVV YV INVENTOR5 Donadd Peccen Georqe De Gross ATTORNEYj United States Patent 3,312,763 GRIENTATION 0F PARTICLES IN ELASTOMER MATERIALS Donald Peccerill, 37 Susquehanna Ave., West Haven, Conn, 06516, and George De Gross, West Haven, Conn.; said De Gross assignor to said Peccerill Filed Nov. 10, 1964, Ser. No. 410,201

9 Claims. (Cl. 264-108) This invention relates to magnets and more particularly to improvements in the manufacture of magnets of elastomeric material having magnetic particles dispersed therein.

In recent years there has become an increasing demand for small strip permanent magnets which are suitable for use in effecting closures and seals. It is generally required that these small permanent magnets be embedded in a material which is easily manipulated so as to fit the contour and space requirements of the devices being constructed. To meet this requirement, the prior art has offered various ferrite and iron compounds embedded within elastomeric or other plastic material. These have generally been formed by mixing the ferrites ground to domain size dimensions with the plastic material, orienting the particles first by a calendering or rolling technique and then, subsequent to the orienting step, magnetizing the particles to provide a permanent magnet.

This technique has generally resulted in magnetic materials, strips or sheets of magnetic materials of relatively low magnetic properties. It is believed that this is a result of the lack of orientation of the magnetic domains of the ferrite particles dispersed within the elastomer material, due to the random orientation of the dipolar magnetic molecules produced by the mechanical rolling deformation. In order to produce small magnets of the strip or sheet type with sufiiciently high magnetic prop erties, the magnetic strips or sheets have heretofore been cut and stacked prior to the application of a permanent setting magnetic field. Thus, the prior art has utilized a three step process, that is, magnetic domain orientation with the aid of rolling or calendering, a subsequent stacking step and then a setting of the ferrite particles with the aid of a high intensity magnetic field to permanently magnetize the ferrites dispersed in the elastomer material.

Additionally, other prior art in this field has utilized the technique of combining ferrite particles with an unpolymerized plastic material in a liquid state and subsequently applying a magnetic field to orient the particles within the liquid unpolymerized material. After this has been accomplished and while the magnetic field is continuously applied, heat is then applied to the material to effect a polymerization of the elastomer material and a fixing of the position of the magnet particles within the elastomer material. This method has two significant disadvantages. A casting is formed of dimensions which are not suitable for hardware or other type of apparatus such as refrigerator doors requiring long thin strips of magnetic material. Further, in its present form, it is not easily adaptable to rolling or mechanical deformation to reduce its dimensions since any mechanical deformation would cause a random reorientation of the magnetic domains of the magnetic material and reduce the magnetic properties of the material.

In view of the foregoing, the principal object of this invention is to provide a new and improved method for producing permanent magnets.

Another object of the invention is to provide a new and improved technique for orienting domains of magnetic particles dispersed within an elastomeric material.

A further object of the invention is to provide a new and improved method of manufacturing sheets or strips of elastomeric material having dispersed therein magnetic particles.

A still further object of the invention is to provide a new and improved method of manufacture for simultaneously reducing the dimensions of an elastomeric material having magnetic material embedded therein and simultaneously orienting and permanently magnetizing the magnetic material.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

In accordance with this invention, a new and improved technique for fabricating permanent magnets is provided by mechanically deforming and applying a magnetic field simultaneously to magnetic particles dispersed within a non-magnetic matrix. In the preferred embodiment of the instant invention, this is accomplished by rolling a non-magnetic matrix, such as an elastomeric material having dispersed therein ferrite particles while simultaneously applying a magnetic field to orient the magnetic domains of the particles and to permanently magnetize the magnetic particles embedded within the elastomeric material.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, the apparatus embodying features of construction, combinations and arrangement of parts which are adapted to effect such steps, and the product which possesses the characteristics, properties, and relation of components, all as exemplified in the detailed disclosure hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

FIG. 1 is a front elevational view partly in section of apparatus for carrying out the method of this invention according to a preferred embodiment of the invention;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 3 is a side elevational view in section showing a modified form of apparatus for carrying out the method according to another embodiment of this invention;

FIG. 4 is a side elevational view partially in section showing alternative apparatus for carrying out the invention;

FIG. 5 is a diagrammatic illustration partially schematic showing a modified form of apparatus for carrying out the method according to this invention; and

FIG. 6 is a diagrammatic illustration showing an alternative apparatus for carrying out the invention.

Referring now to FIG. 1, the apparatus comprises a support 10 to which there is affixed a plurality of bushings 11, 12, 13 and 14, as shown. Positioned in a spaced relationship to support 10 are two work rolls 20 and 21 which are utilized to mechanically deform and compress a material 23 passed therebetween. Roll 20 is provided with two shaft portions 24 and 25, the former guided within support 10 by bushing 11 and the latter guided on support 10 by bushing 13. Roll 21 is likewise provided with two shaft portions 26- and 27, the former supported and guided on support 10 by bushing 12 and the latter supported and guided on support 10 by bushing 14. Shaft portions 24 and 26 extend from bushings 11 and 12 respectively and are coupled to gears 30 and 31 as shown. These gears 30 and 31 are driven in synchronism by a driving pinion gear 32 coupled to a shaft 3 3 of a variable speed motor 34. As such, variable speed motor 'dom during the rolling process.

34 rotates pinion gear 32 to cause gears 30 and 31 to rotate and drive rolls 20 and 21 respectively.

Also coupled to support Itl is a plurality of flanged sleeves 36, 37, 38 and 39, as shown. Sleeve 36 surrounds shaft portion 24 to permit free rotation of shaft 24 and further to permit an electro-rnagnet 40 to be wound as shown about the sleeve. Further, sleeve 37 permits another magnet 41 to be positioned about shaft portion 25. Additionally, shaft portions 26 and 27 of roll 21 are surrounded by two other magnets 42 and 43 as shown in the drawing. Magnets 40, 41, 42 and 43 are coupled to a source of direct energy (not shown) and are wound such that magnetic lines of force in the direction as shown are obtained. In order to obtain the orientation of the lines of force from the four magnets as shown in the drawing, magnets 40 and 41 are wound and coupled such that their poles closest to roll 20 are of north polarity and magnets 42 and 43 have their poles closest to roll 21 of a south polarity.

It is to be understood that the polarities can be reversed as long as the portions closest to the top roll 20 and the bottom roll 21 have the same relationship as above to produce lines of force as shown in the drawing.

Further, coupled to support are four doctor blades 46, 47, 48 and 49 for cleaning rolls 2t} and 21 respectively. Additionally, two guide elements 50 and 51 are provided and coupled to support .10 to guide material 23 being worked on through the apparatus.

In operation, the apparatus shown in FIGS. 1 and 2 acts on material 23 which comprises elastomeric material having magnetic and/ or ferrite particles dispersed therein. The elastomeric material 23 is an elastic substance, such as a synthetic rubber or a plastic having some of the physical properties of natural rubber. For example, the elastomeric material could comprise a plastic of the polyvinyl chloride type. Furt'her, materials such as methyl methacrylate, urea formaldehyde, vinyl acetate, vinyl formaldehyde, buna N, or other suitable materials may be utilized. It is to be further understood that combinations of the above, with natural rubber, or natural rubher with other materials or by itself, may be used as the elastomeric material referred to herein. In the preferred embodiment, barium ferrite particles are preferably utilized as the material which is dispersed within the clastomeric material. It is to be understood that other ferrite materials, such as lead and strontium which exhibit high degrees of magnetic efficiency, could be substituted in place of the above. Further, other materials of the iron type could be utilized in carrying out the process of this invention.

In order to carry out the method according to the invention, material 23 having the ferrite particles dispersed therein is fed through rolls and 21. The rolls are positioned at a distance from each other suchas to cause a reduction in the thickness dimension of the material or sheet 23, being passed theret'hrough. At the same time, a magnetic field is simultaneously applied to the portion of the material undergoing deformation by magnets 40, 41, 42 and 43 in a manner to cause magnetic lines of force, as shown in FIG. 1, to be applied perpendicularly to the top surface of material 23 and through the small dimension of material 23. By simultaneously magnetizing the material and deforming the material, it has been discovered that substantial increases in the magnetic efficiency of the magnet produced is obtained. In fact, the method described herein has provided permanent magnets of the type described exhibiting an appreciable increase in strength in comparison to permanent magnets of the same type manufactured by the prior art methods. It is theorized that this is due to the rolling action permitting the particles to move with a greater degree of free- The mechanical agitation produced by the rolling permits the magnetic particles dispersed within the elastomeric material to be substantially affected by the lines of force passing therethrough. In this manner the magnetic material can be strongly influenced by the magnetic lines of force sothat the magnetic domains of the particles can be oriented in the proper direction while at the same time being permanently magnetized.

In practice, it has been found that by utilizing the simultaneous mechanical deformation with the accompanying magnetic field, magnets are produced with such highly efficient magnetic properties that it is no longer a requirement that the sheets be cut up and stacked in order to produce a permanent highly efficient strip or sheet magnets. Further, this simultaneous technique permits thematerial to be fabricated at less cost and with greater efiiciency, inasmuch as the number of steps required in the technique is substantially reduced.

From the foregoing, it should become apparent that a new and improved process has been provided for fabrication of magnets having substantially enhanced magnetic properties. The improvement is accomplished by simultaneously orienting the magnetic domains and permanently magnetizing the magnetic particles While the particles and elastomeric material are at the same time undergoing mechanical deformation.

As an example of a permanent magnetactually manufactured in accordance with the teachings of this invention, a composition of the following materials by weight was utilized:

8 parts--barium ferrite 1 part--polyvinyl chloride .6 part-plasticizer The polyvinyl chloride could be of the type sold by the designation 2YSA-S by the Union Carbide Company and the plasticizer could be of the type designated as DOP and sold by the Union Carbide Company.

It is to be understood that in place of the rolls as shown with their axes being along a perpendicular line to material 23 passing therethrough, other types of rolling structures such as a calendering roll wherein the axes are off-centered, or rolls such that each roll operates at substantially different rotational speeds could be utilized to provide the mechanical deformation of material 23.

Referring now to FIG. 3, there is shown a modification of the structure of FIG. 1 for performing the method of manufacture according to the instant invention. The apparatus of FIG. 3 comprises a support 60 for mounting three pairs of rolls, shown as 61 and 62, 63 and 64, and 65 and 66, respectively. Rolls 61 through 66 are staggered such that they operate on material 23 to cause a gradual mechanical deformation and reduction in the thickness dimension of said material. At the same time that each of rolls 61 through 66 are mechanically deforming material 23, a magnetic field is being applied as shown in FIGS. 1

and 2, to orient and permanently magnetically set the magnetic particles within the elastomeric material under each of the rolls. Further, the apparatus of FIG. 3 has a guide 70 for guiding the side surface of material 23 and a plurality of doctor blades 71 through 78 are provided for cleaning each of rolls 61 through 66 respectively in the manner previously mentioned with respect to FIGS. 1 and 2.

Thus, an alternate embodiment of an apparatus for.

fabricating magnetic material is disclosed which will reduce the dimensions of a matrix material such as material 23 in a plurality of steps to thereby effect a subtantial reduction in the thickness of the material while at the same time providing a highly efficient magnetic magnet by the simultaneous application of a magnetic field to the strip material 23 while said material is undergoing each of the mechanical deformation steps.

Referring now to FIG. 4, there is shown a further modification of an apparatus for performing the invention. The apparatus comprises a support member on which there are mounted two rolls 86 and 87 as shown. To provide the strip material 23 previously mentioned with regard to FIGS. 1 through 3, there is provided a.

housing 88 having an extrusion screw 89 mounted therein. At one end of housing 88 is an orifice 90 for permitting extruded material to pass therethrough and under rolls 86 and 87. Also coupled to support member 85 is a guide 93 for guiding the extruded material therethrough and two doctor blades 94 and 95 for cleaning rolls 86 and 87. In practice, the elastomeric material having magnetic particles dispersed therein is enclosed within housing 88, such that screw member 89 can, by turning, force a portion of the material through orifice 90 in a sheet form. After leaving orifice 90, the material in the sheet form undergoes a mechanical deformation and reduction in dimension by rolls 86 and 87. Simultaneously, a magnetic field is applied to effect orientation of the magnetic domains of the particles and at the same time to permanently set the magnetic properties of these particles. Thus, there has been provided an alternate structure for carrying out the method of this invention in a sheet material formed by extrusion passed under and through a plurality of rolls which mechanically deform and reduce the thickness of material while at the same time a magnetic field is supplied to the material such that the magnetic lines of force are perpendicular to the top surface of the material.

Referring now to FIG. 5, there is shown a further modification of an apparatus for performing the method according to this invention. The apparatus comprises rolls 20 and 21 for mechanically deforming material 23. Material 23 is of an elastomeric constituency having magnetic particles dispersed therein. There is disclosed four iron core members, 100, 101, 102 and 103 positioned in the same manner as the electromagnets shown in FIG. 1. Each of the cores, 100 through 103 have D.C. windings 110, 111, 112 and 113 wound thereon, respectively. D.C. windings 110 and 111 are connected to a D.C. source 115 and D.C. windings 112 and 113 are coupled to a D.C. source 116. These D.C. sources in conjunction with the D.C. windings and the cores provide an electromagnet for permanently setting and magnetizing the portion of material 23 undergoing mechanical deformation, as previously disclosed in FIG. 1. The cores 100 through 103 also have wound thereon additional A.C. windings 120, 121, 122 and 123, respectively. A.C. windings 120 and 121 are coupled to A.C. source 125 and A.C. windings 122 and 123 are coupled to A.C. source 126. It has been discovered that by applying an A.C. magnetic field to the portion of material 23 undergoing mechanical deformation, to agitate or loosen the magnetic particles prior to applying the setting and orienting the D.C. field, a substantially improved magnet is obtained. It is believed, once again, that this permits freedom of motion of the magnetic particles and the respective domains of the magnetic particles positioned within the elastomeric material 23. The A.C. and D.C. can be controlled by a switching controller 127 which can control a signal so as to first cause the A.C. sources 125 and 126 to be simultaneously switched on and then subsequently turn off these soucres and turn on the D.C. sources 115 and 116. Through the use of high speed electrical switching, it is possible to switch these devices fast enough to agitate the portion of material 23 by the A.C. magnetic while it is undergoing mechanical deformation and still have sufiicient time to correctly the orient and align the magnetic domains of the magnetic particles positioned within material 23 by a D.C. magnetic field. Controller 127 could be a well known switching apparatus, i.e., a step switch arrangement or a ring counter. It is to be understood that the windings as shown in FIG. 5 are merely illustrative and it is therefore to be understood that as long as the D.C. lines of force are formed as shown in FIG. 5 (by the arrows), the B field will be at a maximum and there will be no substantial bucking of the B fields provided by each of the electromagnetics. It has also been discovered that instead of using a sequential pulsing of A.C. and D.C. to first agitate then orient the particles, it is possible to effect agitation and simultaneous orientation by superimposing a small A.C. signal upon the D.C. magnetic field. This can be accomplished by turning on the A.C. sources and 126 and the D.C. sources 115 and 116 simultaneously to thereby superimpose a small A.C. signal upon the D.C. signal, thereby causing a pulsating D.C. to both agitate and simultaneously orient and align the domains to produce a highly efiicient magnetic material.

In FIG. 6 there is shown an additional alternate embodiment wherein the strip of material 23' is mechanically deformed at a plurality of stations (two stations in this instance), by rollers and 141 and then rollers ,142 and 143. By passing material 23 through said rollers at a significantly high rate of speed, it is possible to apply an A.C. magnetic field by the electromagnets and 151 actuated by A.C. source and subsequently by electrogmagnets 152 and 153 coupled to a D.C. source 170, to orient and align the magnetic particles within the elastomeric material. The A.C. field once again is used to agitate and give the magnetic domains a degree of free dom of motion, while it is undergoing mechanical deformation and then the D.C. field is used to align and orient the magnetic particles.

Since many changes could be made to the above described construction and method and many apparently widely different embodiments of the invention could be made without departing from the scope thereof, it is maintained that all matter contained in the above description or shown in the accompanying drawing should be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. The method of producing continuous lengths of solid polymeric magnetic strip wherein the elemental magnets of the strip are substantially oriented in the same polar direction, comprising the step of cold rolling a moving solid polymeric strip having magnetizable particles dispersed therein while simultaneously applying an aligning and polarizing magnetic field providing unidirectional lines of force through the same portion of the strip being cold rolled.

2. The method according to claim 1, wherein the magnetic field is provided by an electromagnet and wherein the electromagnet is in a fixed position with respect to the moving strip.

3. The method of making continuous lengths of solid polymeric magnetic strip wherein the elemental magnets of the strip are substantially oriented in the same polar direction, which comprises cold rolling a moving solid polymeric strip having magnetizable particles dispersed therein to reduce the thickness of the strip while simultaneously applying an aligning and polarizing magnetic field providing unidirectional lines of force through the same portion of the strip being cold rolled.

4. The method of preferentially aligning and polarizing a plurality of magnetizable particles dispersed within a solid polymeric matrix strip, comprising cold rolling a portion of the strip while applying polarizing and aligning magnetic field to the same portion of the strip being cold rolled.

5. The method according to claim 4, in which the magnetic field is provided by an electromagnet.

6. The method according to claim 4, in which the strip portion is reduced in thickness by the cold rolling step.

7. The method according to claim 4, in which the magnetizable particles are selected from the class consisting of barium ferrite, strontium ferrite and lead ferrite.

8. The method of preferentially aligning and polarizing a plurality of magnetizable particles dispersed within a solid polymeric matrix strip, comprising cold rolling a portion of said strip while applying thereto first an alternating magnetic field and then a polarizing and aligning magnetic field.

9. The method of preferentially aligning and polarizing a plurality of magnetizable particles dispersed within a solid polymeric matrix strip, comprising cold rolling a portion of said strip while applying thereto an aligning 7 and polarizing magnetic field having a small pulsating 2,999,271 magnetic field component superimposed thereon. 3,051,988 3,095,262 References Cited by the Examiner 3,117,065 5 3,141,050

UNITED STATES PATENTS Peterman 264-108 XR Baermann. Schwabe. Venerus.

8 Falk et a1. Baermann. Maish et a1. Wooten l1793.4 XR Blume 264108 ALEXANDER H. BRODMERKEL, Primary Examiner.

ROBERT F. WHITE, Examiner.

10 J. H. WOO, Assistant Examiner. 

1. THE METHOD OF PRODUCING CONTINUOUS LENGTHS OF SOLID POLYMERIC MAGNETIC STRIP WHEREIN THE ELEMENTAL MAGNETS OF THE STRIP ARE SUBSTANTIALLY ORIENTED IN THE SAME POLAR DIRECTION, COMPRISING THE STEP OF COLD ROLLING A MOVING SOLID POLYMERIC STRIP HAVING MAGNETIZABLE PARTICLES DISPERSED THEREIN WHILE SIMULTANEOUSLY APPLYING AN ALIGNING AND POLARIZING MAGNETIC FIELD PROVIDING UNDIRECTIONAL LINES OF FORCE THROUGH THE SAME PORTION OF THE STRIP BEING COLD ROLLED. 